Buggy code:
public class Javac extends MatchingTask { private static final String FAIL_MSG = "Compile<seq2seq4repair_space>failed;<seq2seq4repair_space>see<seq2seq4repair_space>the<seq2seq4repair_space>compiler<seq2seq4repair_space>error<seq2seq4repair_space>output<seq2seq4repair_space>for<seq2seq4repair_space>details." ; private Path src ; private File destDir ; private Path compileClasspath ; private Path compileSourcepath ; private String encoding ; private boolean debug = false ; private boolean optimize = false ; private boolean deprecation = false ; private boolean depend = false ; private boolean verbose = false ; private String target ; private Path bootclasspath ; private Path extdirs ; private boolean includeAntRuntime = true ; private boolean includeJavaRuntime = false ; private String fork = "false" ; private String forkedExecutable = null ; private boolean nowarn = false ; private String memoryInitialSize ; private String memoryMaximumSize ; private Vector implementationSpecificArgs = new Vector ( ) ; protected boolean failOnError = true ; protected boolean listFiles = false ; protected File [ ] compileList = new File [ 0 ] ; private String source ; private String debugLevel ; private String compiler = null ; public String getDebugLevel ( ) { } public void setDebugLevel ( String v ) { } public String getSource ( ) { } public void setSource ( String v ) { } public Path createSrc ( ) { } protected Path recreateSrc ( ) { } public void setSrcdir ( Path srcDir ) { } public Path getSrcdir ( ) { } public void setDestdir ( File destDir ) { } public File getDestdir ( ) { } public void setSourcepath ( Path sourcepath ) { } public Path getSourcepath ( ) { } public Path createSourcepath ( ) { } public void setSourcepathRef ( Reference r ) { } public void setClasspath ( Path classpath ) { } public Path getClasspath ( ) { } public Path createClasspath ( ) { } public void setClasspathRef ( Reference r ) { } public void setBootclasspath ( Path bootclasspath ) { } public Path getBootclasspath ( ) { } public Path createBootclasspath ( ) { } public void setBootClasspathRef ( Reference r ) { } public void setExtdirs ( Path extdirs ) { } public Path getExtdirs ( ) { } public Path createExtdirs ( ) { } public void setListfiles ( boolean list ) { } public boolean getListfiles ( ) { } public void setFailonerror ( boolean fail ) { } public void setProceed ( boolean proceed ) { } public boolean getFailonerror ( ) { } public void setDeprecation ( boolean deprecation ) { } public boolean getDeprecation ( ) { } public void setMemoryInitialSize ( String memoryInitialSize ) { } public String getMemoryInitialSize ( ) { } public void setMemoryMaximumSize ( String memoryMaximumSize ) { } public String getMemoryMaximumSize ( ) { } public void setEncoding ( String encoding ) { } public String getEncoding ( ) { } public void setDebug ( boolean debug ) { } public boolean getDebug ( ) { } public void setOptimize ( boolean optimize ) { } public boolean getOptimize ( ) { } public void setDepend ( boolean depend ) { } public boolean getDepend ( ) { } public void setVerbose ( boolean verbose ) { } public boolean getVerbose ( ) { } public void setTarget ( String target ) { } public String getTarget ( ) { } public void setIncludeantruntime ( boolean include ) { } public boolean getIncludeantruntime ( ) { } public void setIncludejavaruntime ( boolean include ) { } public boolean getIncludejavaruntime ( ) { } public void setFork ( String f ) { } public boolean isForkedJavac ( ) { } public String getJavacExecutable ( ) { } public void setNowarn ( boolean flag ) { } public boolean getNowarn ( ) { } public Javac . ImplementationSpecificArgument createCompilerArg ( ) { } public String [ ] getCurrentCompilerArgs ( ) { } public void execute ( ) throws BuildException { } protected void resetFileLists ( ) { } protected void scanDir ( File srcDir , File destDir , String [ ] files ) { } public File [ ] getFileList ( ) { } protected boolean isJdkCompiler ( String compilerImpl ) { } protected String getSystemJavac ( ) { String extension = ( Os . isFamily ( "dos" ) ) ? ".exe" : "" ; File jExecutable = null ; if ( Os . isName ( "aix" ) ) { jExecutable = new File ( ( ( ( System . getProperty ( "java.home" ) ) + "//..//..//sh//javac" ) + extension ) ) ; } if ( ( jExecutable == null ) || ( ! ( jExecutable . exists ( ) ) ) ) { jExecutable = new File ( ( ( ( System . getProperty ( "java.home" ) ) + "//..//bin//javac" ) + extension ) ) ; } if ( ( jExecutable . exists ( ) ) && ( ! ( Os . isFamily ( "netware" ) ) ) ) { return jExecutable . getAbsolutePath ( ) ; } else { <START_BUG> return "javac" ; <END_BUG> } } public void setCompiler ( String compiler ) { } public String getCompiler ( ) { } protected void checkParameters ( ) throws BuildException { } protected void compile ( ) { } public class ImplementationSpecificArgument extends Commandline . Argument { private String impl ; public void setImplementation ( String impl ) { } public String [ ] getParts ( ) { } } }

Fix:
return "javac" + extension ;